Corneal ectasia is a progressive thinning and bulging of the cornea that leads to irregular shape and distorted vision. It can occur as part of conditions like keratoconus or, more rarely, after corneal surgery.
Causes and Mechanism
In ectasia, the collagen framework that normally maintains corneal strength becomes weakened so the cornea stretches forward under normal eye pressure, causing increasing myopia and irregular astigmatism.
- Primary ectasias include keratoconus and pellucid marginal degeneration, often linked to genetic and environmental factors such as eye rubbing.
- Post‑surgical ectasia is an uncommon complication after laser vision correction when residual corneal thickness is insufficient.
- Early signs may be subtle, detected only on topography or tomography.
- Symptoms include ghosting, glare, and frequent prescription changes.
Management
Treatment aims to stabilise the cornea and improve visual quality, using spectacles, rigid or custom contact lenses, corneal cross‑linking, or transplant in advanced cases.
- Corneal cross‑linking strengthens collagen bonds and can slow or halt progression, especially when done early.
- Specialist lenses (RGP, scleral, hybrid) often give clearer vision than glasses by masking surface irregularity.
- Severe scarring or thinning may require lamellar or full‑thickness transplantation.
- Patients are advised to avoid eye rubbing and manage allergies to reduce mechanical stress.
